Common options are described below.
option description
location location can be an x,y coordinate. Alternatively, the text can be placed interactively via mouse by specifying location as locator(1). pos position relative to location. 1=below, 2=left, 3=above, 4=right. If you specify pos, you can specify offset= in percent of character width. side which margin to place text. 1=bottom, 2=left, 3=top, 4=right. you can specify line= to indicate the line in the margin starting with 0 and moving out. you can also specify adj=0 for left/bottom alignment or adj=1 for top/right alignment.

You can use the text( ) function (see above) for labeling point as well as for adding other text annotations. Specify location as a set of x, y coordinates and specify the text to place as a vector of labels. The x, y, and label vectors should all be the same length.